In general, in a lighting apparatus using an LED, such as a street light, a decoration light, and a security light, a substrate thereof to which the LED is mounted is disposed in parallel with the ground. Of course, although a structure in which an installation angle thereof is slightly varied in the front-rear direction and in the right-left direction to adjust an irradiation angle thereof has been proposed, a configuration in which a light emission surface of the LED is arranged in a direction perpendicular to the ground or in a direction almost perpendicular to the ground is hardly found.
In this way, in the lighting apparatus using an LED according to the related art, since the light emission surface of the LED faces the ground, it is difficult to adjust a light distribution pattern of the LED. Accordingly, a structure of a housing for supporting a substrate to which a plurality of LEDs are mounted is changed to change an orientation angle of each of LED groups so as to make the light distribution pattern of the whole lighting apparatus into a desired shape.
Accordingly, in the lighting apparatus using an LED according to the related art, different housings should be made according to use of the lighting apparatus, and there is a problem in that it is impossible or very difficult to adjust the light distribution thereof.
In addition, since heat dissipation fins at an opposite side of the light emission surface of the LED according to the related art are disposed in parallel with the ground, air therein does not perform convection so that a heat dissipation effect is low and a lifespan of the LED is shortened.
For example, Korean Patent Laid-Open Publication No. 2003-0044324 discloses a tunnel lamp using an LED, and more particularly, a tunnel lamp of which an LED substrate is installed in parallel with the road and a housing curved in an L-shaped form is employed, so as to prevent a glare directed toward a driver.
However, since spotlights using an LED according to the related art, including Korean Patent Laid-Open Publication No. 2003-0044324, are installed in parallel with the road surface such that a light emission surface of the LED faces the road surface, the spotlights have a light distribution pattern that meets an inherent light irradiation angle of the LED.
Although there is a difference between light distribution patterns of a general street light and a tunnel lamp, it is difficult to arbitrarily form a light distribution pattern, and a lens for converting the light distribution patterns into a specific light distribution pattern is employed in order to solve the above-mentioned problems.
The lens corresponds to a factor of a LED light which increases a cost, and causes optical loss so as to decrease intensity of illumination. When the lens is employed, since the intensity of illumination to be provided to the road surface decreases, more LEDs should be used to adjust the intensity of illumination of the road surface, which causes an increase in manufacturing costs and an increase in power consumption so as to deteriorate advantages of the LED light.